Recently, various types of display devices are developing in accordance with the development of technologies. In particular, in order to satisfy the needs of a user intending to watch an image with a bigger screen while enhancing portability, study on a foldable display device of which a plurality of displays are located at a foldable housing is in active progress.
A user may use a foldable display device in a folded state to watch a single display only or may use the foldable device in an unfolded state to watch a plurality of displays at a time depending on a necessity.
Meanwhile, in case of 3 foldable display device, 2 display units are shown to a user with a different height in a state that the 2 display units are separated from each other in a medium unfolded state. Hence, it is necessary to have a technology applied to the medium unfolded state.